ar-15 failing to feed issue

G

garrett8781

Member
Rating - 100%
21   0   0
took out my ar for the first time,

10.5 ballistic advantage 1:7 5.56 barrel
armalite upper receiver
armalite milspec bcg
(all brand new)

shooting .223 barnaul 62grain SP

failed to feed on both pmags and stanag with the round getting jammed on the lip of the chamber
ive also tried 2 different gas blocks and tubes
the bolt will also not hold open after last round is fired

now i havent tried any different ammo yet but i was planning on buying 3-4 different types and testing to see if it was the ammo itself however i have read about m4 feed ramps giving this issue sometimes. i am new to the AR scene. is this feed ramp in spec or is this what would cause this issue? or am i overthinking it

https://imgur.com/WgrH7Q1
 
If it doesn't hold open, generally you need more gas. If your gas block isn't adjustable, it's giving it all. Are you positive the gas block lined up with your barrels gas port ? Standard buffer/buffer spring ? Is it all lubed up, quite wet (ARs like oil.), not dry ?

You could also try giving the chamber a vigorous cleaning with an AR chamber brush. My 10.5 build had similar issues with a dirty chamber from manufacture. Not really visible top the eye either.
 
223 barnaul 62grain SP is most likely under powered, that caused the bolt's failure to move to the rear enough to engage the bolt stop.

The SP bullet maybe too blunt at the tip, the M4 feed ramp designed for the pointy M855 could be too steep for it and have the SP bullet driven too high up.

I suggest you try it with some regular AE or Winchester 55gr FMJ or 62gr FMG.
 
What buffer are you using?

Also ammo should never be the problem. Your gun should run what ever you put in it. Factory anyways.
 
I’m having the exact same issue with my mystery box ar. Manually, it functions normal. Put 1 round in and fire it, case ejects, but bolt does not lock back. More than one round, first case ejects, but second round jams. This is with AE fmj and 4 different mags. I’ll be keeping an eye on this thread.
 
What buffer are you using? Also if you have a scale weigh it in G.


DAgunlvr said:
I’m having the exact same issue with my mystery box ar. Manually, it functions normal. Put 1 round in and fire it, case ejects, but bolt does not lock back. More than one round, first case ejects, but second round jams. This is with AE fmj and 4 different mags. I’ll be keeping an eye on this thread.
Click to expand...
 
The one that came with it. It’s a mystery box full ar kit from TNA. I don’t have a scale that could measure that.
 
If the buffer is to heavy there will be to long of a dwell time . You need a lighter buffer .there is like 4 different weights. Also make sure you have a carbine length buffer spring and not a rifle one.
 
I would try different ammo as well. My 7.5" usually won't lock open with pmcs or that steel cased Russian stuff (forget the name of that one). Locks open with federal and handloads.
 
JTF# said:
If the buffer is to heavy there will be to long of a dwell time . You need a lighter buffer .there is like 4 different weights. Also make sure you have a carbine length buffer spring and not a rifle one.
Click to expand...

A few people have mentioned this and I tend to agree. At 10.5" it should be a lighter buffer and spring. Sometimes people insist on running an H buffer because they want mil spec but have a short barrel that is anything but so there was a couple of occasions where I ended up remming of the gas port. I wouldn't suggest that because it is much easier to change the buffer and spring or go with a commercial buffer and spring. Any butt stock companies make for mil spec they make for commercial now, anyways.

Just out of curiosity, what BCG are you using? You mentioned that it does not hold open on the last round but it does hold open when you manually cycle the gun, right? And personally, I would not look at ammo to begin with. A properly set up AR should run pretty much any type of ammo you put through it, IMHO. Just look at those cheap M&P15s and Norc CQAs, they pretty much eat everything. They're nothing fancy but they're set up to run.
 
Garaldtao said:
A few people have mentioned this and I tend to agree. At 10.5" it should be a lighter buffer and spring. Sometimes people insist on running an H buffer because they want mil spec but have a short barrel that is anything but so there was a couple of occasions where I ended up remming of the gas port. I wouldn't suggest that because it is much easier to change the buffer and spring or go with a commercial buffer and spring. Any butt stock companies make for mil spec they make for commercial now, anyways.

Just out of curiosity, what BCG are you using? You mentioned that it does not hold open on the last round but it does hold open when you manually cycle the gun, right? And personally, I would not look at ammo to begin with. A properly set up AR should run pretty much any type of ammo you put through it, IMHO. Just look at those cheap M&P15s and Norc CQAs, they pretty much eat everything. They're nothing fancy but they're set up to run.
Click to expand...

thanks for the replies, it wont be a couple of weeks before i can hit the range to try some different ammo.

the BCG is an armalite mil spec and the buffer is just a milspec carbine buffer/spring
 
You must log in or register to reply here.
Back
Top Bottom